1. Field of the Invention
This disclosure relates generally to semiconductor devices with integrated thin-film transistor (TFT) circuitry, for example displays with epitaxially grown light emitting diodes (LEDs) integrated with corresponding TFT pixel drivers.
2. Description of Related Art
Active matrix liquid-crystal displays and organic light emitting diode (OLED) displays combined with thin-film transistor technology are becoming increasingly popular in today's commercial electronic devices. These displays are widely used in laptop personal computers, smartphones and personal digital assistants. Millions of pixels together create an image on a display. The TFTs act as switches to individually turn each pixel on and off, rendering the pixel light or dark, which allows for convenient and efficient control of each pixel and of the entire display.
However, conventional TFT-LCD displays and TFT-OLED displays suffer from low light efficiency, causing high power consumption and limited battery operation time. Conventional inorganic semiconductor light emitting diodes (LED) have demonstrated superior light efficiency, which makes active matrix LED displays more desirable for battery operated electronics. However, in active matrix LED displays, combining TFT driver circuitry with light emitting diodes (LED) has drawbacks. For example, the TFT driver circuitry typically is fabricated on one wafer and the LEDs fabricated on a separate wafer. Devices on the two wafers may then be connected by solder bumps bonding the wafers. Alternately, LEDs may be individually picked and placed onto the wafer containing the TFT circuitry. However, these types of processes are inefficient and costly.
As a result, there is a need for better integration of TFT circuitry with non-TFT circuitry (e.g., LEDs).